Core/Misc: Remove unneeded files

These 3 BlackRock Mountain scripts can be removed from source:

- boss_anubshiah.cpp
- boss_gorosh_the_dervish.cpp
- boss_grizzle.cpp

They already removed from the creatures in DB, and are currently causing
DBErrors.

src/server/game/Scripting/ScriptLoader.cpp

@@ -102,11 +102,8 @@ void AddSC_boss_galvangar();
 void AddSC_boss_vanndar();
 void AddSC_blackrock_depths();               //Blackrock Depths
 void AddSC_boss_ambassador_flamelash();
-void AddSC_boss_anubshiah();
 void AddSC_boss_draganthaurissan();
 void AddSC_boss_general_angerforge();
-void AddSC_boss_gorosh_the_dervish();
-void AddSC_boss_grizzle();
 void AddSC_boss_high_interrogator_gerstahn();
 void AddSC_boss_magmus();
 void AddSC_boss_moira_bronzebeard();
@@ -804,11 +801,8 @@ void AddEasternKingdomsScripts()
     AddSC_boss_vanndar();
     AddSC_blackrock_depths();               //Blackrock Depths
     AddSC_boss_ambassador_flamelash();
-    AddSC_boss_anubshiah();
     AddSC_boss_draganthaurissan();
     AddSC_boss_general_angerforge();
-    AddSC_boss_gorosh_the_dervish();
-    AddSC_boss_grizzle();
     AddSC_boss_high_interrogator_gerstahn();
     AddSC_boss_magmus();
     AddSC_boss_moira_bronzebeard();